CSF3 and cancer: Metastatic tumors, on the other hand, induce chemotaxis of circulating neutrophils by secreting large amounts of G-CSF; these recruited neutrophils are mostly immature and immunosuppressive, promoting cancer metastasis (73).Actually, only fully differentiated neutrophils expressing CXCR2 are permitted to enter the Circulatory system and subsequently infiltrate the corresponding tissues.